It has been demonstrated that in a diffuser of a centrifugal compressor, ribbed vanes forming a logarithmic spiral or circular arc have the effect of energizing the boundary layer flow without sacrifice to the core flow. The result is increased range and efficiency to the compressor. Full vanes are known to improve efficiency over vaneless designs, but at the expense of range.
The need for further improvements in range and efficiency led to the developments of the present invention.